The invention relates to a photometric assembly for a camera, and more particularly, to a photometric assembly for use in a camera of the reflective photometry type in which light from an object being photographed which passes through a taking lens is reflected by a film surface or the surface of a shutter blind of a focal plane shutter and is guided by a reflecting member to impinge on a photoelectric transducer element which is provided for the purpose of photometry.
In a camera utilizing a focal plane shutter, and in particular, in a single lens reflex camera of the reflective photometry type in which light reflected from the surface of a first shutter blind or a film surface is determined, a reflecting member is utilized to direct the reflected light to a photoelectric transducer element which is disposed in the bottom of a dark box for the purpose of photometry. A reflective photometry assembly can be provided which is responsive to the amount of light received by the element for effecting a control to provide a proper exposure. When such an assembly is constructed, the transducer element and an IC chip which forms an exposure control circuit can be formed as one integral package which may be directly disposed on a printed circuit board. This avoids the need to route a signal current from the transducer element which has a minimal magnitude to spaced or remote points, thus eliminating the likelihood of malfunctioning in response to extraneous noises or a breaking of lead wires. The incorporation of the transducer element and the IC chip into an integral unit reduces the cost and the space requirement, affording the advantage of allowing an effective utilization of the available space.
However, a point with this assembly is the fact that only the light which is reflected by the reflective member must be directed to impinge on the transducer element. If the light reflected by the blind surface or the film surface directly impinges on the transducer element if the proportion is small, the distribution of light receiving sensitivity is disturbed, preventing an accurate photometry. Consequently, it is necessary to provide a shield member or members which prevent a direct impingement of the reflected light from the blind or the film surface onto the transducer element. However, when shielding the reflected light from the film surface which directly impinges on the transducer element, the impingement of the light from the reflecting member onto the transducer element must not be intercepted or otherwise an accurate photometry is again prevented. In addition, the provision of the shield member involves the likelihood that a reduced magnitude of a photometric output may degrade the performance of an associated camera. Hence, it is important that the shield member be located so as to reliably prevent the direct impingement of the reflected light from the blind or the film surface without intercepting the incident light from the reflecting member.